AIB is currently investigating the accidental overcharging of some customers.

The bank said today it was working to rectify the situation as soon as possible.

It is understood some customers were double-charged on March 25 and then again on March 26 for some transactions, it is not known how many consumers have been affected.

"AIB regrets any disruption to our customers this morning arising from duplicate transactions processed on their accounts.

"This issue arose after a file of debit card transactions was processed twice in error. We are currently reversing the impact on customer accounts and expect this to be completed by 2pm today," the bank said in a statement.

"We apologise for any inconvenience caused and will ensure no customers will be adversely affected."